The Flemish carbon monitoring network 'Cmon' aims to monitor organic carbon stocks in soils under different land uses (cropland, grassland, forest, nature and residential) and their evolutions. A preliminary study by Sleutel et al (2021) elaborated the outline of this monitoring network. Besides organic-carbon stocks to 1 m depth, total nitrogen, pH and soil texture are also determined in at 2600
monitoring plots over a 10-year period. All sites will be resampled every 10 years thereafter. The first Cmon working year ran until 30 June 2022. In this first working year, the focus was mainly on the protocols for sample names, sample pre-treatments, analytical techniques, etc. This is to ensure that the measurement uncertainties due to the sample names and analyses are smaller than the actual differences in carbon build-up or carbon losses within and across land uses. All this ensures that the results can eventually be used to adjust LULUCF reporting and forecasts i.e. to substantiate whether e.g. agricultural soils or residential areas store or lose carbon. In this first working year, much attention was paid to harmonisation and storage of data so that all validated results are stored in one database (i.e. Databank Subsoil Flanders) and can be processed and accessed from there. Finally, the Flemish Geotheek was adapted so that the Cmon soil samples can be stored as the first long-term soil samples in conditioned conditions.